The present invention relates to a silicon carbide fiber having a low specific electric resistance value and excellent mechanical properties including high tensile strength and tensile modulus, and to a method of manufacturing the same.
There has been known heretofore a method of manufacturing a silicon carbide fiber comprising, for example, steps of spinning a polycarbosilane material into threads or yarns, heating the spun yarns at a temperature ranging between 50.degree. C. and 400.degree. C. in an oxidizing gas atmosphere to produce antimelt-treated fibers and heating said antimelt-treated fibers at a temperature of above 1000.degree. C. and up to 1500.degree. C. in an atmosphere of inert gas such as a nitrogen gas.
The silicon carbide fiber obtained as above can be made to have various specific electric resistance values by changing the heating condition in which the antimelt-treated fibers are further heated in an inert gas atmosphere. This silicon carbide fiber manufactured as above has excellent mechanical properties including high tensile strength of 200-350 kg/mm.sup.2 and high tensile modulus of 18-25 t/mm.sup.2 in its specific electric resistance range of 10.sup.2 -10.sup.8 (.OMEGA..multidot.cm).
However, a silicon carbide fiber so manufactured according to the foregoing method as to have a low specific electric resistance value such as 10.sup.-1 -10.sup.2 (.OMEGA..multidot.cm) has a problem that its tensile strength is lowered to 50-100 kg/mm.sup.2 and its tensile modulus also is lowered to 5-10 t/mm.sup.2.
Therefore, it is the object of the present invention to provide a silicon carbide fiber having a low specific electric resistance and excellent mechanical properties, thereby solving the above-mentioned problem.